Technical Field
The present disclosure relates to equalization of Single-Carrier Frequency Division Multiple Access) SC-FDMA signals via adaptive frequency-domain decision feedback equalizers (AFD-DFEs).
Description of Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Orthogonal Frequency Domain Multiple Access (OFDMA) is a multiple access technique which has been adopted in many standards like ETSI DVB-RCT as described in European Telecommunications Standards Institute (ETSI), “Digital video broadcating (DVB); Interaction channel for Digital Terrestrial Television (RCT) Incorporating Multiple Access OFDMA,” ETSI EN301 958, vol. 1.1.1, 2002, D. Prendergast, B. Caron, and Y. Wu, “The Implementation of a Return Channel for ATSC-DTV,” IEEE Transactions on Broadcasting, vol. 53, pp. 521-529, June 2007, WiFi as described in IEEE Std 802.11-2007, “IEEE Standard for Information technology-Local and metropolitan area networks—Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,” 2007, and WiMAX as described in IEEE Std 802.16-2009, “IEEE Standard for Local and metropolitan area networks—Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems,” 2009.
Single-Carrier Frequency Division Multiple Access (SC-FDMA) is a multiple access technique which has been adopted in wireless broadband communication systems such as the Long Term Evolution (LTE) standard described in 3GPP, “Physical Channels and Modulation,” ETSI TS 136.211 V10.0.0, 2011. SC-FDMA has comparable complexity and performance to that of the Orthogonal Frequency Division Multiple Access (OFDMA) as described in Q. Wang, C. Yuan, J. Zhang, and Y. Li, “Frequency Domain Soft-Decision Feedback Equalization for SC-FDMA with Insufficient Cyclic Prefix,” International Journal of Computer Science (IJCSI), vol. 9, no. 6, pp. 103-108, 2012, but with an additional benefit of having a low Peak Average Power Ratio (PAPR), which helps in reducing power consumption and increasing battery life in mobile terminals.
SC-FDMA is selected as a standard technique for the uplink LTE. The sensitivity analysis of SC-FDMA is reported in K. Raghunath and A. Chockalingam, “SC-FDMA Versus OFDMA: Sensitivity to Large Carrier Frequency and Timing Offsets on the Uplink,” IEEE Global Telecommunications Conference (GLOBECOM), pp. 1-6, November 2009, and it can be shown that for large Carrier Frequency Offset (CFO) the performance of SC-FDMA can get worse than OFDMA.
The use of the Frequency-Domain Linear Equalizer (FD-LE) in SC-FDMA may not be effective for frequency-selective fading channels with spectral nulls which result in significant noise enhancement. The Frequency-Domain Decision Feedback Equalizer (FD-DFE) may be a more attractive solution when dealing with these kind of scenarios.